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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

MAPPING LAND COVER LAND USE CHANGE IN MBEERE DISTRICT, KENYA

Maluki, Peter Masavi 14 August 2007 (has links)
No description available.
2

Évolution de l’évolution de l’occupation du sol (1950-2025) et impacts sur l’érosion du sol dans un bassin versant méditerranéen / Long term prediction of soil erosion (1950-2025) in a Mediterranean context of rapid urban growth and land cover change

Roy, Hari Gobinda 15 September 2016 (has links)
La question du changement de la couverture terrestre est devenue importante dans le monde entier au cours des dernières années, non seulement pour les chercheurs, mais aussi pour les planificateurs urbains et les écologistes qui préconisent l'utilisation durable des terres dans l'avenir. En Europe méditerranéenne, les caractéristiques de couverture du sol ont considérablement changé depuis la Seconde Guerre mondiale en raison des activités humaines intensives, de la croissance de la population, et de l'étalement urbain et touristique. La plupart des études antérieures sur les changements de l’occupation du sol dans la région méditerranéenne se sont centrées sur un problème particulier et / ou ont décrit un type spécifique de changement de la couverture terrestre. Peu de recherches ont pris en compte les transformations de plusieurs catégories d’occupation du sol en même temps. De même, rares sont les travaux qui considèrent plusieurs variables dans le changement de l’occupation du sol au cours du temps, au-delà des traditionnels effets de l’altitude et de la pente. Nous souhaitons ici intégrer la variété des catégories et des composantes d’évolution. En outre, si certaines études à propos de la modélisation des mutations de la couverture terrestre se concentrent sur les variables d’influence, peu se penchent sur l’influence de la période historique et des échelles de temps différentes sur la prédiction. Ainsi, dans cette thèse, les changements de l’occupation du sol ont été prédits en utilisant différentes échelles de temps pour évaluer les impacts de la période historique dans la prédiction de la carte de la couverture terrestre d'ici 2025. Enfin, si l’étendue spatiale varie dans les différentes recherches, il semble utile de s’interroger sur les effets de la taille du terrain d’étude et de la résolution des cellules prises en compte, dans la prédiction. Les transformations de l’occupation du sol ont un impact significatif sur la dégradation des terres, y compris l'érosion des sols. / The European Mediterranean coastal area has experienced widespread land cover change since 1950 because of rapid urban growth and expansion of tourism. Urban sprawl and other land cover changes occurred due to post-war economic conditions, population migration, and increased tourism. Land cover change has occurred through the interaction of environmental and socio-economic factors, including population growth, urban sprawl, industrial development, and environmental policies. In addition, rapid expansion of tourism during the last six decades has caused significant socioeconomic changes driving land cover change in Euro-Mediterranean areas. Mediterranean countries from Spain to Greece experienced strong urban growth from the 1970’s onwards, and a moderate growth rate is projected to continue into the future. Land cover change can result in environmental changes such as water pollution and soil degradation. Several previous studies have shown that Mediterranean vineyards are particularly vulnerable to soil erosion because of high rainfall intensity and the fact that vineyards are commonly located on steeper slopes and the soil is kept bare during most of the cultivation period (November to April) when precipitation is at its highest. The main objective of this thesis is to predict long-term soil erosion evolution in a Mediterranean context of rapid urban growth and land use change at the catchment scale. In order to achieve this, the following specific aims have been formulated: (i) to analyze the spatial dynamics of land cover change from 1950 to 2008; (ii) to compare the impact of historical time periods on land cover prediction using different time scales; (iii) to test the impacts of spatial extent and cell size on LUCC modeling; and (iv) to predict the impact of land cover change on soil erosion for 2025.
3

Analyzing Landscape Trends on Agriculture, Introduced Exotic Grasslands and Riparian Ecosystems in Arid Regions of Mexico

Mendez-Estrella, Romeo, Romo-Leon, Jose, Castellanos, Alejandro, Gandarilla-Aizpuro, Fabiola, Hartfield, Kyle 18 August 2016 (has links)
Riparian Zones are considered biodiversity and ecosystem services hotspots. In arid environments, these ecosystems represent key habitats, since water availability makes them unique in terms of fauna, flora and ecological processes. Simple yet powerful remote sensing techniques were used to assess how spatial and temporal land cover dynamics, and water depth reflect distribution of key land cover types in riparian areas. Our study area includes the San Miguel and Zanjon rivers in Northwest Mexico. We used a supervised classification and regression tree (CART) algorithm to produce thematic classifications (with accuracies higher than 78%) for 1993, 2002 and 2011 using Landsat TM scenes. Our results suggest a decline in agriculture (32.5% area decrease) and cultivated grasslands (21.1% area decrease) from 1993 to 2011 in the study area. We found constant fluctuation between adjacent land cover classes and riparian habitat. We also found that water depth restricts Riparian Vegetation distribution but not agricultural lands or induced grasslands. Using remote sensing combined with spatial analysis, we were able to reach a better understanding of how riparian habitats are being modified in arid environments and how they have changed through time.
4

Integrated Spatiotemporal Characterization of Dust Sources and Outbreaks in Central and East Asia

Darmenova, Kremena 07 April 2006 (has links)
The potential of atmospheric dust aerosols to modify the Earth's environment and climate has been recognized for some time. However, predicting the diverse impact of dust has several significant challenges. One is to quantify the complex spatial and temporal variability of dust burden in the atmosphere. Another is to quantify the fraction of dust originating from human-made sources. This thesis focuses on the spatiotemporal characterization of sources and dust outbreaks in Central and East Asia by integrating ground-based data, satellite multi-sensor observations, and modeling. A new regional dust modeling system capable of operating over a span of scales was developed. The modeling system consists of a dust module DuMo, which incorporates several dust emission schemes of different complexity, and the PSU/NCAR mesoscale model MM5, which offers a variety of physical parameterizations and flexible nesting capability. The modeling system was used to perform for the first time a comprehensive study of the timing, duration, and intensity of individual dust events in Central and East Asia. Determining the uncertainties caused by the choice of model physics, especially the boundary layer parameterization, and the dust production scheme was the focus of our study. Implications to assessments of the anthropogenic dust fraction in these regions were also addressed. Focusing on Spring 2001, an analysis of routine surface meteorological observations and satellite multi-sensor data was carried out in conjunction with modeling to determine the extent to which to this integrated data set can be used to characterize the spatiotemporal distribution of dust plumes at a range of temporal scales, addressing the active dust sources in China and Mongolia, mid-range transport and trans-Pacific, long-range transport of dust outbreaks on a case-by-case basis. This work demonstrates that adequate and consistent characterization of individual dust events is central to establishing a reliable climatology, ultimately leading to improved assessments of dust impacts on the environment and climate. This will also help to identify the appropriate temporal and spatial scales for adequate intercomparison between model results and observational data as well as for developing an integrated analysis methodology for dust studies.
5

Understanding and Mapping Land-Use and Land-Cover Change along Bolivia's Corredor Bioceancio

Redo, Daniel J. 2010 May 1900 (has links)
The Corredor Bioceanico is a major transportation project connecting the agricultural heartlands of South America to the Atlantic and Pacific coasts. The final link is in southeastern Bolivia - an underdeveloped area that is home to two indigenous groups and globally-significant woodlands and wetlands. Infrastructure developments - comprising a major highway upgrade, revitalized railway services and increased flows along gas pipelines to Brazil - pose major threats to livelihoods and the region's ecological integrity. There are two broad objectives: (i) to map and quantify the spatial patterns of land change using a time-series of coarse and medium resolution satellite imagery; and (ii) to understand the socio-economic and political drivers of change by linking household surveys and interviews with farmers; environmental, climatic, and political data; and classified satellite imagery. Overall, large-scale deforestation has occurred along the Corredor Bioceanico for mechanized commercial production of oil-seed crops such as soybeans and sunflower. The significance of these findings is that agriculture-driven deforestation is pushing into sensitive areas threatening world-renowned ecosystems such as the Chaco, Chiquitano and Pantanal as well as noteworthy national parks. Though quantity remains relatively small compared to other parts of South America, rates of forest loss match or exceed those of more publicized regions such as Rondonia or Mato Grosso, Brazil. Moreover, rates of forest loss are accelerating linearly with time due to policies implemented by incumbent president Evo Morales. Results also show that in the first years of cultivation, pasture is the dominant land-use, but it quickly gives way to intensively cropped farmland. The main findings in terms of percentage area cleared according to forest type is that farmers appear to be favoring transitional forest types on deep and poorly drained soils of alluvial plains. Semi-structured interviews with farmers and representatives of key institutions illustrate that price determined by the global market is not proportionally the most dominant motive driving LULCC in the lowlands of Santa Cruz, Bolivia - an area seen as a quintessential neoliberal frontier.
6

Using ecosystem services to understand the impact of land cover change: a case study of the upper San Pedro watershed

Chan, David Joseph January 2013 (has links)
In arid and semiarid environments, various natural and anthropogenic stressors have resulted in land cover change that has negatively impacted the ecological integrity of the landscape. Society, however, relies on many ecological processes and functions provided by the landscape to enhance its wellbeing. The direct and indirect benefits society receives from the landscape are collectively termed "ecosystem services." The overarching goal of this thesis was to examine how the landscape has changed and to analyze how these changes impact the ecosystem services supplied by the landscape. The Upper San Pedro watershed in southeastern Arizona and northern Sonora was used as a case study to link land cover change with an array of ecosystem services to understand the spatiotemporal dynamics of ecosystem service supply. To accomplish this, a multitemporal land cover dataset for the watershed was updated to extend the temporal coverage to 37 years across 5 land cover datasets. Indicators serving as proxy variables for a variety of ecosystem services were assessed for each land cover class. This linkage between land cover and ecosystem services enabled an analysis of the tradeoffs and synergies within the array of services each land cover class can provide. Combined with the multitemporal land cover dataset, the spatiotemporal dynamics of potential ecosystem service supply were analyzed across the watershed for a 37 year period. Rather than examining the impacts of land cover change on the biophysical aspects of the environment, this approach enables land managers and decision makers to explore the implications of a changing landscape on human wellbeing.
7

Landscape and biodiversity change in the Willmore Wilderness Park through repeat photography

Fortin, Julie 30 April 2018 (has links)
Repeat photography, the process of retaking an existing photograph from the same vantage point, can give insight into long-term land cover dynamics. I advance the use of repeat photography to quantify landscape change in two ways: first, I demonstrate that rigorous field and post-processing methods can lead to highly accurate co-registration of images; second, I show that oblique photographs can provide land cover composition information similar to conventional satellite (Landsat) imagery for dominant land cover types, and that oblique photographs are better at resolving narrow or steep landscape features. I then present a novel approach to evaluate long-term biodiversity change using repeat photography: I measure land cover composition in 46 historical and modern photograph pairs in the Willmore Wilderness Park, Alberta, Canada, and use that land cover information as input into species-habitat models to predict the probability of occurrence of 15 songbird species. I show that coniferous forest cover increased over the past century, leading to a homogenization of the landscape which increased the probability of occurrence of forest-adapted species but negatively impacted non-forest-adapted species. / Graduate / 2019-04-18
8

Understanding the Role of Vegetation Dynamics and Anthropogenic induced Changes on the Terrestrial Water Cycle

Valayamkunnath, Prasanth 03 April 2019 (has links)
The land surface and atmosphere interact through complex feedback loops that link energy and water cycles. Effectively characterizing these linkages is critical to modeling weather and climate extremes accurately. Seasonal variability in vegetation growth and human-driven land cover changes (LCC) can alter the biophysical properties of the land surface, which can in turn influence the water cycle. We quantified the impacts of seasonal variability in vegetation growth on land surface energy and water balances using ecosystem-scale eddy covariance and large aperture scintillometer observations. Our results indicated that the monthly precipitation and seasonal vegetation characteristics such as leaf area index, root length, and stomatal resistance are the main factors influencing ecosystem land surface energy and water balances when soil moisture and available energy are not limited. Using a regional-scale climate model, we examined the effect of LCC and irrigation on summer water cycle characteristics. Changes in biophysical properties due to LCC reducing the evapotranspiration, atmospheric moisture, and summer precipitation over the contiguous United States (CONUS). The combined effects of LCC and irrigation indicated a significant drying over the CONUS, with increased duration and decreased intensity of dry spells, and reduced duration, frequency, and intensity of wet spells. Irrigated cropland areas will become drier due to the added effect of low-precipitation wet spells and long periods (3-4% increase) of dry days, whereas rainfed croplands are characterized by intense (1-5% increase), short-duration wet spells and long periods of dry days. An analysis based on future climate change projections indicated that 3–4 °C of warming and an intensified water cycle will occur over the CONUS by the end of the 21st century. The results of this study highlighted the importance of the accurate representation of seasonal vegetation changes and LCC while forecasting present and future climate. / Doctor of Philosophy / The land surface and atmosphere interact through complex feedback loops that link energy and water cycles. Effectively characterizing these linkages is critical to accurately model weather and climate extremes. We quantified the influence of human-driven land cover change (LCC), in this case, LCC associated with irrigated agriculture, and seasonal vegetation growth on the water cycle using a regional climate model and ecosystem-level observations. Our results indicated that monthly precipitation and seasonal vegetation growth are the main factors influencing land surface energy and water balances when soil moisture and solar energy are not limited. Our results showed that irrigation-related LCC reduced summer precipitation over the contiguous United States (CONUS), with an increased number of dry days (days with less than 1 mm precipitation) and reduced hourly, daily, and summer precipitation totals. Irrigated cropland areas are becoming drier due to the combined effects of low precipitation and long dry days, whereas rainfed croplands are characterized by intense short-duration precipitation and long dry days. Climate change analyses indicate that 3–4 °C of warming and an intensified water cycle will occur over the CONUS by the end of the 21st century. The results of this study highlight the importance of the accurate representation of LCC while forecasting future climate.
9

Examination of Urban Expansion and its Environmental Impacts using Remotely Sensed Time-Series Imagery in Ulaanbaatar, Mongolia / モンゴル国ウランバートルにおける時系列衛星画像を用いた都市域拡大とその環境影響に関する考察

Tsutsumida, Narumasa 24 March 2014 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(地球環境学) / 乙第12828号 / 論地環博第8号 / 新制||地環||24(附属図書館) / 31315 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)准教授 西前 出, 教授 渡邉 紹裕, 教授 小方 登 / 学位規則第4条第2項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM
10

Land Cover Change in a Savanna Environment. A Case Study of Bawku Municipal

Adusei, Kwame 06 November 2014 (has links)
No description available.

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